Tuesday 6 September 2011 06.50 EDT
First published on Tuesday 6 September 2011 06.50 EDT

An international cult of oddness is hoping for a fillip from one of the mathematical rarities of the western calendar.

Californian enthusiasts have declared Odd Day on Wednesday 7 September and called for all manner of pranks and eccentricities to mark its unusual status.

This consists of three consecutive odd numbers in the traditional style of date abbreviation – 7/9/11, a phenomenon which happens only five times a century. Americans are being rallied to the cause in particular because the first date in the 20th century's sequence – 1/3/5 – fell 13 months after the Wright brothers made their first flight.

This is the sort of odd fact which retired teacher Ron Gordon of Redwood City, south of San Francisco, wants to celebrate during the 24 hours of Odd Day and Night.

His website is offering the appropriately odd international prize of $791.10 (£490.98) to be shared between the best Odd parade, Odd ode or Odd commemoration of the date.

The enthusiasm has yet to go fully global but has reached as far as the Punxsutawney Spirit newspaper in Pennsylvania. Its suggestions passed on from Gordon included watching "sea odders" and trying to figure out why the word "odd" has an odd number of letters while its opposite "even" has the opposite.

The Gordons also point out that Americans and Canadians need not be content with five Odd Days a century, thanks to their dating shorthand's reversal of the day and the month, compared with the system used by most of the rest of the world.

Celebrating US Odd Day on 9 July this year, Ron Gordon told the Wall Street Journal: "These dates are just cute, funky things that you stumble over. I feel compelled to say: 'Look what's coming'."

He will not settle back when the calendar resumes its humdrum course on Thursday 8 September. His arsenal, used to excite students about the potential of "boring" maths, also includes Square Root Days and Palindromic Days. The next of the latter in the US falls on 11 November this year – 11/2/11 – and its connections with Armistice Day are exactly the sort of link which gives a glow to Oddites' lives.